Why do I fail the test?

Question about the task

Mirror image

Java Core, Level 9, Lesson 11

Resolved

Input seems as requested.

1. Read a file name from the console. Read the contents of the file.
2. For each line in the file:
2.1. reverse the order of all characters.
2.2. display the result.
3. Close the streams.

Example input file:
I'm a programmer. Amigo

Example result:
.remmargorp a m'I ogimA

Requirements:

The program must read the file name from the console (use BufferedReader).
The BufferedReader used for reading input from the console must be closed after use.
The program must read the file's contents (use FileReader).
The file input stream (FileReader) must be closed.
The program should display all of the characters from the file in reverse order.

package com.codegym.task.task19.task1926; /* Mirror image /Users/lilianetop/Desktop/taak1925Input.txt */ import java.io.*; public class Solution { public static void main(String[] args) { String input = ""; StringBuilder sb = new StringBuilder(); try (BufferedReader reader = new BufferedReader(new InputStreamReader(System.in))) { input = reader.readLine(); } catch (IOException e) { e.printStackTrace(); } try(BufferedReader reader2 = new BufferedReader(new FileReader(input))) { while(reader2.ready()){ String line = reader2.readLine(); //reverse the line not the entire document //this is not working as it adds 2 line together and doesn't reverse the last line //sb.reverse().append(line + "\n"); sb.append(line + "\n"); } } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } System.out.println(sb.reverse().toString()); } }

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Nouser

Level 36 , Germany

12 January 2021, 11:03

solution

Cause you should just output the result I'd suggest following: read a line (give the reader a more speaking name like in?)

while (in.ready()) {

grab the line and save it in a string...

String line = in.readLine();

to reverse the line you either can loop over it from the back to the first and directly output to the console.. or you use StringBuilder...

new StringBuilder(line).reverse();

and of course output that. Alltogether that my look similar to:

while (in.ready())
    System.out.println(new StringBuilder(in.readLine()).reverse());

Don't be mad with me if it doesn't work, haven't tried it and instead typed it here into the text box

Liliane Top Backend Developer at Procura

12 January 2021, 11:23

Hi Nouser, without you I would have given up. The problem was that it would reverse the entire document and I didn't see it till I numbered the lines in my testFile. I do have to append the line first before I can reverse it. But I check your code as well. And then I will refactor it in some clean code💪

String[] lines = sb.toString().split("\n");
        //step 2: iterate over the lines 1-by-1
        for (String line : lines) {
            //StringBuilder sb2 = new StringBuilder();
            //step 3: take the first line append it to a StringBuilder to be able to use the StringBuilder's reverse() method it and print it to console
            //move to next line
            System.out.println(new StringBuilder().append(line).reverse());
        }

Liliane Top Backend Developer at Procura

12 January 2021, 11:26

You code work and very clean 🧼

Nouser

Level 36 , Germany

12 January 2021, 11:34

puh... ;)